Volume 18, Number 7—July 2012
Research
Loss of Household Protection from Use of Insecticide-Treated Nets against Pyrethroid-Resistant Mosquitoes, Benin
Table 2
Protection against Anopheles gambiae s.l. mosquitoes for persons sleeping under in-use mosquito nets before and after treatment with 18 mg/m2 lambdacyalothrin in houses in northern vs. southern sites, Benin, 2008*
Area, net condition | Treatment of nets | Blood fed, no. (%) | OR (95% CI) | p value | aOR (95% CI) | p value |
---|---|---|---|---|---|---|
Northern (pyrethroid-susceptible mosquitoes) |
Before | 810 (46) | 1 | 1 | ||
After | 1,041 (16) | 0.22 (0.18–0.28) | <0.001 | 0.34 (0.26–0.44) | <0.001 | |
No. holes | ||||||
<10 | Before | 503 (45) | 1 | 1 | ||
After | 850 (14) | 0.20 (0.16–0.27) | <0.001 | 0.26 (0.20–0.34) | <0.001 | |
>10 | Before | 307 (48) | 1 | 1 | ||
After | 191 (24) | 0.34 (0.23–0.51) | <0.001 | 0.37 (0.27–0.64) | <0.001 | |
Size of holes, cm2 | ||||||
<15 | Before | 59 (36) | 1 | 1 | ||
After | 217 (17) | 0.38 (0.20–0.73) | 0.003 | 0.38 (0.20–0.73) | 0.003 | |
>15 | Before | 751 (47) | 1 | 1 | ||
After | 824 (16) | 0.21 (0.17–0.27) | <0.001 | 0.21 (0.17–0.27) | <0.001 | |
Southern (pyrethroid-resistant mosquitoes) |
Before | 268 (20) | 1 | 1 | ||
After | 424 (23) | 1.19 (0.81–1.73) | 0.37 | 1.14 (0.73–1.76) | 0.57 | |
No. holes | ||||||
<10 | Before | 111 (18) | 1 | 1 | ||
After | 200 (21) | 1.15 (0.55–1.67) | 0.28 | 1.17 (0.62–1.81) | 0.31 | |
>10 | Before | 165 (27) | 1 | 1 | ||
After | 224 (25) | 0.89 (0.56–1.42) | 0.64 | 0.89 (0.56–1.41) | 0.63 | |
Size of holes, cm2 | ||||||
<15 | Before | 115 (19) | 1 | 1 | ||
After | 189 (23) | 1.31 (0.74–2.36) | 0.35 | 2.59 (1.26–5.37) | 0.01 | |
>15 | Before | 153 (21) | 1 | 1 | ||
After | 235 (23) | 1.10 (0.67–1.8) | 0.70 | 1.09 (0.18–1.80) | 0.713 |
*OR, odds ratio; aOR, OR adjusted for condition of nets and household size.
1Deceased.